Band width controller

ABSTRACT

A control means for the adjustment of the band width of a moving band of continuous material which passes over a plurality of tensioning bars and is subject to deviations in its width due to its inherent properties in such an environment, comprises at least one bar presenting a curved surface to one face of the continuously moving band, said surface, upon engaging said face, causing said band to spread or become narrower in accordance with the disposition of said curved surface. The bar is actuated by an amplifier-controller and servomotor which is constantly error sensitive in that error-measuring means are provided downstream being in engagement with said band to measure the error and effect the input signal to the amplifier-controller. In alternate embodiments a plurality of curved surfaces are presented to one or more faces of said band, said surfaces being movable by means which are controlled either independently or commonly.

United States Patent [72] Inventors William Kirk Wyatt Lansdale; John R.Brownell, Telford, both of, Pa. [2!] Appl. No. 835,546 [22] Filed June23, 1969 [45] Patented July 13, 1971 [73] Assignee Turbo Machine CompanyLansdale, Pa.

[54] BAND WIDTH CONTROLLER 6 Claims, 6 Drawing Figs.

[52] US. Cl 226/18,

19/65 T [51] int. Cl B65h 25/26 [50] Field of Search 226/11, 15, l823;29/65 T, 66 T; 26/63 [56] References Cited UNITED STATES PATENTS 3, l 7i ,579 3/1965 Robertson 226/23 3,305,896 2/l967 Rayfield ABSTRACT: Acontrol means for the adjustment of the band width of a moving band ofcontinuous material which passes over a plurality of tensioning bars andis subject to deviations in its width due to its inherent properties insuch an environment, comprises at least one bar presenting a curvedsurface to one face of the continuously moving band, said surface, uponengaging said face, causing said band to spread or become narrower inaccordance with the disposition of said curved surface. The bar isactuated by an amplifier-controller and servomotor which is constantlyerror sensitive in that error-measuring means are provided downstreambeing in engagement with said band to measure the error and effect theinput signal to the amplifier-controller. In alternate embodiments aplurality of curved surfaces are presented to one or more faces of saidband, said surfaces being movable by means which are controlled eitherindependently or commonly.

PATENTEUJUL i 3 l97i INVENTORS. William Kirk Wyatt BY John R. BrownellWf M ATTORNEYS PATENIEU JUL 1 a ram [3592.371 SHEET 2 UF 3 INVENTORS.William Kirk Wyotr BY John R. Brownell ATTORNEYS.

PATENfTEDJuu 3am 3,592,371

' sum 3 or 3 INVENTORS.

William Kirk Wyufl BY John R. Brownell MsPM ATTORNEYS.

BAND WIDTH CONTROLLER BACKGROUND OF THE INVENTION This invention relatesto servomechanisms, and more particularly to a servomechanism for use incontrolling the band width ofa moving band of continuous textilematerial.

Textile material, such as tow is commonly processed in apparatus whereinthe tow is drawn from a bag or barrel and fed through a plurality ofbars to apply tension to the tow and to present it to a processingapparatus in the form of a continuously moving band. In order to processthe band properly, it is necessary to maintain the band width as near touniform as possible, as for example, when it is fed into a machine, suchas a stapler.

SUMMARY OF THE INVENTION Our invention provides an apparatus foradjusting the band width of a moving band of continuous material, suchas filamentary tow. It comprises a means for spreading or narrowing thetow or other similar material in response to input signals means and theapparatus receiving the tow. This means includes one or more bars whichare pivotally mounted to rock toward or away from at least one face ofthe band of material,

bar tends to compress the band together producing a smaller band width.Conversely, the convex bar tends to spread the material producing awider band.

An error-sensing means, continuously measures the degree of error inband width from a desired norm, and the frame is pivoted in responsethereto so that the band width is constantly adjuste Accordingly it isan object of our invention to provide a servomechanism for controllingthe band width ofa continuously moving band of material.

This and other objects will become apparent from the followingdescription with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view ofaportion of an apparatus for handling a moving band of material showingthe most preferred embodiment of our invention partially broken away andin operative relation to a band of material disposed in said apparatus;

FIG. 2 is a schematic diagram of the servosystem for the embodimentshown in FIG. 1;

FIG. 3 is section taken as indicated by the lines and arrows 33 in FIG.1, with alternate positions shown in phantom;

FIG. 4 is an enlarged elevation of a portion of the apparatus shown inFIG. 1, partially broken away, with alternate positions shown inphantom;

FIG. 5 is a view taken as indicated by the lines and arrows 5-5 in FIG.I; and

FIG. 6 is a perspective view of an alternate embodiment of ourinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS with respect to the faces ofthe 2 Referring to the figures, FIG. I

shows a portion of an apwidely spaced-apart guide bars, to a firmertension imparted by wrapping the tow around closely particular problemof band width control, rather than that of the wandering or control oflateral displacement of the band.

As shown in FIG. I the portion of the apparatus designated 10 comprisesa frame I2 having mounted to it a fixed, I

To control the band width, we have provided a servomechanism representedschematically by the system shown in FIG. 2. This system comprises apower source designated generally 30, an error-sensing meansdesignated'generally 40, and a controller designated generally 50.The'syst em shown is a pneumatic system, but it will be understood thatthe controls could be hydraulic, electric or operated by other wellknown in the frame 12. The axis of of the guide'shafts I4, I6, 18, 20,22 and 24. The shaft 54 is always in contact with a face of the band 26.

In the preferred embodiment, two control bars are provided to change thewidth of the band. These control bars can be more easily referred to bythe disposition of their curvatures tow band 26. Thus, control bar 56can be referred to as a concave control bar and control bar 58 can bereferred to as a convex control bar.

In FIGS. 1 and 3 both the convex and concave control bars are engagedwith the band 26. Thus, the band is first narrowed passes over the bar58 under tension between the shaft 54 and the guide bar 18. It will beapparent that these bars are interchangeable in their relative positionswith respect to the line of travel of the band. Thus when handling verynarrow material it is desirable to purposely keep the band wider thanthe desired width by using the spreader bar 58 upstream of the narrowingcontrol bar 56, thus allowing the narrowing bar to act as the ultimatecontrol to reduce the band width to that desired just as it passes thecontrol point.

It will further be apparent that various other adjustments or changes inthe mechanism could be made by those skilled in the art. For example, itis possible to separately mount the bars on separate pivoted frames, orto run the material over the concave bar only, keeping the convex barout of engagement in the normal condition and bringing it intoengagement only when necessary, or to reverse this procedure and placethe convex bar normally in engagement with the band while maintainingthe concave bar spaced from the face of the tow band and bringing itinto engagement only when necessary. However, we have found that bymounting both bars in the same pivotally mounted frame and maintainingboth in contact with the belt or band, we have been able to achieve theoptimum degree of control of the width of the band.

We further discovered that by sensing the position of one tensioned edgeof the band in close proximity to the control means we are able toaccurately control the band width. In order to accomplish this, we haveprovided a sensor 42, shown in greater detail in FIG. 4 which isnormally spring biased by the spring 44 to rotate in a clockwisedirection about a shaft 46 passing therethrough. The shaft 46 is affixedto the frame 48 which is mounted in any suitable fashion in theapparatus as by welding it to the support frame 63 which is fixedlyattached to the frame 12. The sensor 42 is so positioned that its leadend 43 lies against the edge 27 FIG. 1 of the band 26. The sensor ispreferably on the order of one-half inch wide and curved outwardly awayfrom the band so as not to snag on the edge 27 of the band. Springbiasing by the spring 44 is sufficient to keep the sensor in contactwith the edge as the band traverses laterally, that is, transversely tothe direction of travel indicated by the arrows FIGS. 1 and 3, asillustrated by the phantom positions FIG. 4.

As shown in FIG. 5 the sensor 42 is preferably disposed to overlie theupper face of the band 26. This is accomplished by mounting the sensorat an angle as shown. In this matter the edge 27 will be turned slightlydownwardly as it passes the sen sor, but will resume its normalorientation in the band as it passed over the next bar. This feature ofthe invention effectively prevents the edge from being rolled or foldedupon itself.

Any error sensed by the sensor 42 is transmitted through the servosystemto the controller 50 which is moved in order to make a correction. Weshall now describe this system in some detail. Referring particularly toFIGS. 2 and 4, the sensor 42 is in a position wherein the band width isnarrower than the optimum desired at the sensing point. Thus the sensorhas rotated clockwise slightly from the normal line designated N. Thenormal line is a line through the pivot point or axis of the shaft 46which would normally be parallel to the edge 41 of the sensor 42 whenthat edge lies in the same plane as, and in engagement with, edge 27 ofthe band 26. In this position no signal is generated and this is theoptimum normal position in which the band width is to be consideredconstant.

In the normal position the edge 41 is spaced from the surfaces of thetwo valve plungers 70 and 72. Each valve is spring-biased open by thesprings 71 and 73 respectively so that air passing through the lines 74and 75 respectively will exit through the bleed holes 76 and 77respectively. The lines 74 and 75 are continuously pressurized from asource of con trolled pressure 30 shown in FIG. 2. These lines areconnected to the ends ofa pneumatic cylinder 80 which is attached to theframe 12.

It is desirable that the cylinder be mounted so as to be able to pivotand for this purpose a track 13 is provided on the arm extending fromthe frame 12. A shaft 17 extends from the side of the cylinder throughthe track 13 and is journaled in a bearing on its outer end which isretained in fixed position against the arm 15 by any suitable means (notshown) so that the cylinder is free to pivot about the' shaft 17' andyet is retained against the arm 15.

Within the cylinder there is a piston 82 FIG. 2 having a piston rod 84extending through a suitable seal at the end of the cylinder, said rodbeing pivotally connected as by pin 85 FIG. 3 to the frame 52. Thus whenthe piston 82 is moved axially within the cylinder 80, the piston rod 84causes pivotal movement of the frame 52 about the axis of the shaft 54.

In the normal position the pressure is equal in lines 74 and 75 and thepressure on either side of the piston 82 in the cylinder 80 is equal.Consequently the frame 52 is maintained in a fixed position. When theband 26 is narrowed as shown in the full view in FIG. 4, the end 43 ofsensor 42 follows the edge 27 of the band and the sensor 42 is rotatedclockwise. As it rotates, it first takes up the gap between the edge 41and the plunger 70, and then it depresses the valve plunger and closesthe bleed hole 76. This causes pressure to build up in the line 74 andconsequently the pressure behind the piston 82 in the cylinder 80 isgreater than that ahead of the piston and in line 75. Thus the pistonwill be forced to the left when viewed as in FIG. 2, and the rod 84 willmove to the left causing the frame 52 pivot in a counterclockwisedirection about the axis of the shaft 54. The frame 52 would then assumethe position shown in phantom designated A in FIG. 3. Thus the concaveor narrowing control bar 56 will be removed from engagement with theband 26 and the band will pass freely from control rod 16 across shaft54. Furthermore, the convex or broadening control bar 58 will bedisplaced so as to put a greater tension on the band and spread it evenfurther. Thus the band will be widened as it passes over the bar 18 andthe bar 20.

As the band gets wider the edge 27 forces the sensor 42 to rotatecounterclockwise toward its normal position. When it is once again inits normal position, both vent holes are open and the pressure on eitherside of the piston is the same. The piston will then remain in thisposition until a further error is sensed.

If the band should get wider than desired, the sensor would move to theposition shown in phantom in FIG. 4 causing the valve plunger 72 toclose the vent hole 77 and increase the pressure in the line therebyforcing the piston to the right and rotating the frame 52 in a clockwisedirection. This would have the effect of reducing the contact which thecontrol bar 58 has with the face of the band and increasing the contactwhich the control bar 56 has with the face of the band as shown by thephantom position designated B in FIG. 3. Thus the band would be narrowedand the sensor would return to its normal position.

When a sensor of the type described is used the spacing between the face41 of the sensor and the valve plungers 70 and 72 to an extentdetermines the sensitivity of the device. Thus if the face 41 wasconstantly in contact with the valve plungers, the range or permissibledeviation which the band width could take would be very narrow, sinceresponse to pivotal movement of the sensor would be almostinstantaneous. However, when a gap or space is left between the face 41and the valve plungers (as previously described), permissible deviationrange is provided whereby the band width can vary within acceptablelimits without any correction being made by the apparatus. Of course,other factors can be changed in order to afi'ect this range. Forinstance, the respective distances between the points of contact of theface 41 with the valve plungers and the axis of the shaft 46, and thepoint of contact of the band with the lead end 43 and the axis of theshaft 46 can be varied within the scope of this invention to affect therange.

FIG. 6 shows an alternate embodiment of our invention in which aplurality of sensors are used and in which the band width is stronglypermanently biased in one direction while being controlled in the otherdirection.

In this embodiment a modified frame 102 is provided wherein the shaft 54is fixedly connected to the frame 102 and is mounted in bearings in theframe 12. However, the outwardly disposed end of the shaft 54 isinterconnected by means of member 104 with the outwardly disposed endsof the shafts 56 and 58. The member 104 increases the fixed stability ofthe shafts with respect to one another and allows the shaft 56 to bear agreater load. Further, while the frame 102 pivots about the axis of theshaft 54 as in the previous embodiment, both control shafts are disposedto the same side of the pivot shaft, rather than on opposite sidesthereof. Herein the web 26 is always drawn across the narrowing concavecontrol arm 56 and then across the shaft 54. Thus the band 26 isconstantly narrowed. The pneumatic piston and cylinder 80 is the same asthat previously described and is connected to frame 102 to pivot itabout the axis of the shaft 54. Upon appropriate movement, thebroadening control arm 58 is brought into contact with the face of theband 26 to spread the band. Thus the upper bar is constantly trying toconverge the tow to a minimum width, whereas the lower bar 58intermittently contracts the tow in order to widen it out again.

A pair offeelers or sensors 110 and 112 are mounted on and insulatedfrom a rod 114 which is fixedly connected to the frame 12 (in anysuitable manner) so as to extend across the band 26. These feelers arepreferably made of spring steel or similar material and are springbiased to lay against the band or to come-in contact with the metal bar116 if a band is not disposed between them and the bar. The bar 116 andthe feelers 110 and 112 are connected by means of an electrical circuit(not shown) in which each feeler coacts with the rod as a switch. Theelectric circuit controls the air pressure in the lines 118, 120 to theair cylinder 80 by any suitable means, such as a three-way solenoidactuated valve (not shown) and thus controls the positioning of thepiston 82 within the cylinder. 1

The system shown is a make-or-break system in that the control bar 56 isconstantly condensing the material flowing past it and it is only whenthis material contracts beyond a predetermined acceptable limit that anychange is made in the position of frame 102. In the normal condition,the bar 56 constantly narrows the band 26 and the bar 58 either widensthe band to a desired limit or does not engage the band at all. Shouldthe band become too narrow and slip from its position between either orboth of the feelers 110, 112 and the bar 115, the feelers would make acircuit to cause movement of the frame 102 in a counterclockwisedirection about the shaft 54. This movement brings the convex bar 58into engagement with the band 26. As the band widens it will eventuallyrun between the feelers and bar 116 thereby breaking the circuit andallowing the frame to return to its original position.

' It will be apparent to those skilled in the art that various changesin the functions performed by the switch circuits 110l16 and 112-116could be made in order to vary the reactions on the frame 102. Furtheradditional feelers and circuits could be used to obtain results similarto those previously described. For example the switch circuit 112-116could be used to widen the band while the switch circuit 110-416 couldbe used to rock the frame 102 in a clockwise direction about the axes ofthe shaft 54 and thereby disengage the convex control bar 58 from theface of the band 26 and allow the concave control bar 56 to once againnarrow the band. Additional modifications could be made within the scopeof our invention, as for instance by providing a second set of feelersspaced parenthetically from the first set of feelers to set an outerlimit for the width of the band. Once again these could be used toremove or lessen the contact of the control bar 58 with the band 26.

Thus it is apparent that the controls can be used in a variety of on-offways, as by way of further example, where the band is normally widenedby the bar 58 and maintained between the feelers and the circuits arenormally closed, so that when the band becomes wider and breaks one ofthe circuits, this actuates the frame 102. As the band width decreasesto a position within the feelers again, the switches will close acircuit thereby allowing the f4ame to return to its original position.

Any of these actions will continue in a pulsing manner, thus maintaininga constant bandwidth range as the tow flows continuously t rough themachine. By placing the control frame 102 as far upstream as practicablefrom the point in which the tow is to be delivered at an acceptable bandwidth, it is possible to minimize the effects of any small deviations inband width. Further the point at which error is sensed should bedownstream of the control frame, and as close to it as practicablc.

The principle shown in the alternate embodiment (FIG. 6 of the drawings)of having sensors along both edges of the band can easily be applied tothe preferred embodiment by those skilled in the art within theprinciple and scope of this invention.

It will be understood that various other changes in the details,materials and arrangement of parts which have been herein described andillustrated in order to explain the nature of this invention, may bemade by those skilled in the art within the principle and scope of theinvention as expressed in the following claims.

It will further be understood that the Abstract of the Disclosure" setforth above is intended to provide a nonlegal technical statement of thecontents of the disclosure in compliance with the Rules of Practiceofthe United STatesPatent Office, and is not intended to limit the scopeof the invention described and claimed herein.

What we claim is:

1. In an apparatus handling a moving band of continuous material passingover a plurality of bars, the improvement comprising:

a. a frame pivotally mounted in said apparatus;

b. a plurality of bars extending from said frame to pivot therewith,said bars comprising at least one bar having a convex curve with respectto a face of said moving band, at least one bar having a concave curvewith respect to a face of said moving band and at least onesubstantially straight bar disposed between said convex and concave barsin the path of travel of said band;

. means engaging said frame for pivoting said frame and bringing thecurved portion of at least one of said curved bars into contact withsaid band; and

d. sensor means for monitoring the width of said band and controllingsaid last mentioned means.

2. The invention of claim 1 wherein said sensor means comprises at leastone member engaging and overlying the edge of said band and beingmovably mounted in said apparatus; means for holding said member againstsaid edge so that said member follows the movements thereof, and meansengaging said member and responsive to the movements thereof forcontrolling said means for pivoting said frame.

3. The invention of claim 1 wherein at least one curved bar and saidsubstantially straight bar are maintained in continuous contact withsaid band, and said means engaging said frame is responsive to saidsensor means for bringing the curved portion of said other curved barinto contact with said band.

4; The invention of claim 3 wherein said concave bar is maintained incontinuous contact with said band.

5. The invention of claim 1 wherein said convex and concave bars are onopposite sides of the pivot point of the frame.

6. The invention of claim 1 wherein the ends of at least some of saidbars remote from said frame are fixedly connected to one another.

1. In an apparatus handling a moving band of continuous material passingover a plurality of bars, the improvement comprising: a. a framepivotally mounted in said apparatus; b. a plurality of bars extendingfrom said frame to pivot therewith, said bars comprising at least onebar having a convex curve with respect to a face of said moving band, atleast one bar having a concave curve with respect to a face of saidmoving band aNd at least one substantially straight bar disposed betweensaid convex and concave bars in the path of travel of said band; c.means engaging said frame for pivoting said frame and bringing thecurved portion of at least one of said curved bars into contact withsaid band; and d. sensor means for monitoring the width of said band andcontrolling said last mentioned means.
 2. The invention of claim 1wherein said sensor means comprises at least one member engaging andoverlying the edge of said band and being movably mounted in saidapparatus; means for holding said member against said edge so that saidmember follows the movements thereof, and means engaging said member andresponsive to the movements thereof for controlling said means forpivoting said frame.
 3. The invention of claim 1 wherein at least onecurved bar and said substantially straight bar are maintained incontinuous contact with said band, and said means engaging said frame isresponsive to said sensor means for bringing the curved portion of saidother curved bar into contact with said band.
 4. The invention of claim3 wherein said concave bar is maintained in continuous contact with saidband.
 5. The invention of claim 1 wherein said convex and concave barsare on opposite sides of the pivot point of the frame.
 6. The inventionof claim 1 wherein the ends of at least some of said bars remote fromsaid frame are fixedly connected to one another.